Santiago Casilla out four weeks with hamstring injury — SF Giants call up George Kontos

The results of Santiago Casilla’s MRI are in: Grade 2 strain of his right hamstring. He’s expected to miss four weeks.

The Giants placed Casilla, who was hurt running to first base in the ninth inning Wednesday, on the disabled list and called up reliever George Kontos from Triple-A Fresno.

Santiago Casilla

San Francisco Giants relief pitcher Santiago Casilla, center, is helped off the field after injuring himself while running out a ground ball against the Colorado Rockies in the ninth inning of the Giants’ 5-1 victory in a baseball game in Denver on Wednesday, May 21, 2014. (AP Photo/David Zalubowski)

Matt Cain remains on the roster and will be re-evaluated when the team returns to San Francisco. He also strained his right hamstring — his is a Grade 1 strain — on a third-inning pitch Wednesday. It’s uncertain if he’ll miss his next start.

Manager Bruce Bochy, who said he told Casilla not to swing before the at-bat, discussed the play moments ago and said he was shocked with the reliever’s speed to first base.

“I don’t think that hamstring has ever seen that type of speed from his legs,” Bochy said. “He said, ‘I knew not to run, but my adrenaline got going and I took off.’ ”

Bochy added, “I said, ‘Don’t swing. You don’t have to swing.’ He said, ‘I’m good, Papi.’ He took the first two, and I didn’t think he was swinging. You assume it’s a baseball game, and they play baseball and they’ll be OK. Fortunately, these guys are competitors, and sometimes they forget. I take responsibility. I should’ve called time out and said, ‘That’s it, don’t swing again.’ ”

Casilla did, bounced to shortstop Troy Tulowitzki and collapsed while crossing the bag.

“Relievers, they live for that,” Bochy said. “They want that one at-bat. They talk about it. (Casilla) is always joking and walking around with a bat, saying, ‘Let me hit, let me hit.’ Part of the game is to let them have fun. It is a game. You think it’s a low-risk situation, you saw what happened. It’s like these guys got to touch the stove to find out.”

Last month, another Giants reliever, David Huff, sustained a quadriceps injury running to first base (also at Coors Field) and went on the DL. Bochy reiterated he’ll put out the word for pitchers that they shouldn’t necessarily go all out on the bases.

“We’ve got to learn from this,” Bochy said. “I’ll take responsibiilty now, but you guys got to be smart, too, realizing we’re not looking for you to beat out an infield hit. Same with the starters. But like I said, they’re playing a game. They’ve done this since Little League. They want to get out there and compete.”